Writing board



Feb. 13, 1951 M. BUXBAUM ET AL 2,541,497

WRITING BOARD Filed July 28, 1950 2 Sheets-Sheet l INVENTOR5. MACBUXBAUM. M05 LEBENSF'EILD.

Feb. 13, 1951 M. BUXBAUM ET AL WRITING BOARD 2 Sheets-Sheet 2 Filed July28, 1950 INVENTORS MAC. BUXBALJM.

Mos LEIBENSFELD.

ATTORNEYS.

Patented Feb. 13, 1951 WRITING BOARD Mac Buxbaum and Moe Lebensfeld,Flushing,

N. Y., assignors to lihe Royal Tot Manufacturing Company, Brooklyn, N.Y., a partnership Application July 28, 1950, Serial No. 176,310

. 3 Claims.

This invention pertains to writing or marking boards made of syntheticresinous materials or compositions, and which are adapted for marking orwriting thereon with chalk crayons or similar marking material.

Chalk is a friable material which has little, if any, adhesiveness, andin order for chalk crayons to produce a legible mark on a writingsurface, the surface must be abrasive and have pockets or projectionswhich will hold the chalk once the chalk has been removed from thecrayon. Slate which is commonly used as a writing board or blackboardhas a naturally abrasive surface composed of pits with jagged edges, butslate is not completely satisfactory as a writing board because it isheavy, is difficult towork and cannot readily be made in various colors.Furthermore, slate is comparatively expensive and may be fracturedeasily.

Composition Writing boards for use with chalk crayons have heretoforebeen constructed which do not have the above-mentioned objectionablefeatures of slate, but on the other hand, these boards have not been assatisfactory as slate in other respects. For example, the boards are notimpervious to moisture so that after a number of washings to remove alltraces of chalk, their surfaces peel, do not dry quickly and/or becomepale or smooth and the boards themselves may warp. In addition, thecolored surface on such boards is usually very thin so that after arelatively short period of use, the writing surface wears away exposinga backer of differently colored material or material which is unsuitablefor chalk crayon writing purposes.

Both slate and the known types of composition boards may be stained bysuch materials as paint, grease, etc., and with some types ofcomposition, it is difficult, if not impossible, to remove undesiredsubstances, such as wax, gum, etc., from the surface of the writingboard by the use of suitable solvents without damaging the writingsurface.

A writin board should also be relatively hard and rigid to withstand thepressures applied during the writing processes and to provide a steadysurface which will produce sharp, clean lines without marring. Slate isinherently hard and is sufficiently rigid in ordinary sizes, especiallyin the thicknesses usually required, to prevent fracture of the slateboard during handling. However, not all composition boards aresatisfactory in these respects.

It is an object of this invention to provide a chalk writing board whichis light in weight,

simple and inexpensive to manufacture and which is an improvement overthe writing boards of the prior art.

Although it is known to manufacture sheets or plates of resinousmaterials, composed of or containing thermoplastic or thermosettingsynthetic resin, such sheets or plates, as conventionally produced, arenot suitable for marking or writing thereon with a chalk crayon, or thelike, by reason of their high gloss surface finish, resulting from thehighly polished tooled steel and often chromium plated molds, glassplates, or the like, employed for molding the same. Even when such moldsare provided with a stipple or grooved surface for imparting a contourand decorative effect to the surface of the molded resinous article, theresulting surface of the article is likewise not suitable for marking orwriting with chalk, crayon, or the like, thereon because it does nothave sufficient abrading effect.

In accordance with the present invention, we propose to make writing ormarking boards of synthetic resinous materials or compositionsincorporating the same, by molding the same into sheets, plates or thelike, and thereupon subjecting a surface or surfaces of these sheets orplates to a sanding, sand blasting, machining or engraving operation,thereby to roughen the surface into the form of myriads of small jaggedabrading projections, which we have discovered are ideally adapted toabrading chalk crayons and similar materials, for marking or writingpurposes.

For making up these writing sheets or plates, we may employ any of thewell known thermoplastic or thermosetting resins, which may be employedas such, or in conjunction with suitable filler materials for moldingpurposes, or, in the case of the thermosetting resins, may be made upinto the form of laminated plastic sheets or plates.

Thus, for the thermoplastic resins, we may employ any of thevinyl resinswhich are polymerizable into hard relatively rigid state, or polystyreneor the methacrylate resins. For the thermosetting resins, we may employany of the phenol-aldehyde, phenol-melamine or urea-aldehyde resins, andthe like, which may be employed in the form of molding compositions infinely comminuted form, alone or in admixture with such filler materialsas wood flour, powdered mineral oxides, talc, etc.

Preferably, however, we make our writing boards of laminated plasticmaterials consisting of superimposed sheets of paper, cotton cloth ormat, or glass fiber cloth or mat, etc., impregnated with andconsolidated under combined heat and pressure by a thermosettingsynthetic resin of the character aforesaid.

The above-described sheets or plates are strong, rigid andself-supporting, even though they may be relatively thin. Hence, theymay be used as writing boards without further modification but they mayalso be surrounded by frames, either fastened thereto or integraltherewith or they may be mounted on a backing material, such as wood,pressed board, sheets or panels of other resinous materials, etc.Furthermore, such sheets or plates are light in weight, long lasting,easy to work and impervious to moisture and other liquids and may bemade in a variety of colors.

The various objects and advantages of the invention and the inventionitself may be better understood by reference to the following detaileddescription of specific embodiments, given by way of example only, inconnection with the accompanying drawings, in which:

Fig. 1 is a perspective view of a resinous sheet or plate prepared inaccordance with our invention;

Fig. 2 is a greatly enlarged fragmentary perspective view of the sheetor plate shown in Fig. 1 and taken along the line 2-2 indicated in Fig.1;

Fig. 3 is a perspective view, partly in section, showing a resinoussheet prepared in accordance with our invention and applied to a backer;

Fig. 4 is a perspective view, partly in section,

of a composite writing board prepared in accordance with our invention;

Fig. 5 is a perspective view, partly in section, of a writing boardprepared in accordance with our invention and having a frame integraltherewith; and

Fig. 6 is a perspective view of a plurality of plates prepared andassembled in accordance with our invention.

In Fig. 1, there is shown a sheet or plate iii having a front surface IIand a back surface 12. The plate which may have any desired shape orsize and which may have any desired color is relatively rigid andself-supporting and may be used as a writing board without furthermodification.

'The plate It may be prepared in any one of several ways. prepared bymolding under heat and pressure in a known manner any of the well knowntypes of resins which after molding and at room temperature haverelatively hard surfaces. resins may, for example, be a vinyl resinwhich is polymerizable, polystyrene or methacrylate resin.Alternatively, the resin may be a thermosetting resin of thephenol-aldehyde, phenolmelamine or urea-aldehyde type. The resins may beemployed'in the form of molding compositions in a finely comminutedform, alone or in admixture with such filler materials as wood flour,powdered mineral oxides, talc, etc.

In the preferred form of the invention, the plate It is made byimpregnating sheets of fibrous material, such as paper, cloth, etc.,with a thermosetting resin and by subsequently consolidating the sheetsand the resin by applying heat and pressure to the laminated structure.

In this form, the plate is, relatively rigid, al-

though it may be very thin and it is substantially unaffected bytemperature.

After the plate has been prepared by one of For example, the plate maybe The the above methods, one or both of the surfaces is roughened bysanding, sand blasting, machining or engraving. The roughening processis of such a nature that the glossy finish which is obtained during themolding process is not only dulled but also the surface of the plate iscovered with fine scratches. These scratches may or may not be visibleto the naked eye and in the preferred form of the invention, thescratches are so fine and so distributed that the surface of the plateappears to be substantially continuous. However, the depth and size ofthe scratches should be suificient to abrade and hold chalk from acrayon when it is drawn across the surface of the plate in a normalmanner, i. e., gently but firmly. We have found, for example, that whenthe surface is sanded, a paper of roughness equal to grade 8-0 flintpaper or coarser should be employed and preferably the paper should havea roughness in the range from grade 2-0 to grade 1.

When the surface of the plate H] is roughened by sanding, the sandingmay be carried out in only a single direction across the surface of theplate, producing scratches and hence a series of projections on thesurface which are substantially unidirectional, as illustrated on thesurface II in Fig. 1. When the projections are substantiallyunidirectional, a chalk crayon drawn across the surface in a directionperpendicular to the scratches tends to produce a better defined markthan when the chalk crayon is drawn across the surface in anotherdirection, such as in the direction of scratching, for example.Therefore, it is preferable that the scratching of the surface becarried out in at least two directions. These two directions may bemutually perpendicular, for example, but they may have other angles ofintersection and they may be parallel or at angles to the edges oftheplate.

The greatly enlarged section shown in Fig. 2 illustrates the types ofsurfaces which are produced on the plate when it is subjected to sandingin the manner indicated above. The top surface l2 shown in Fig. 2illustrates the type of surface which is obtained when the plate is,

sanded in two mutually'perpendicular directions, and the bottom surfacell illustrates the type of surface obtained when the plate is sanded inone direction only. It will be noted that the surface I2 comprises aplurality of projections generally extending in substantially mutuallyperpendicular directions and the projections are of irregular shape andsize. The surfaces shown in Fig. 2 illustrate only approximately thearrangement of projections which is obtained when the plate I0 issanded, and the height of the projections is exaggerated with respect tothe thickness of the plate it] normally employed for a writing board.

If instead of substantially unidirectional projections, projectionsextending in a pluralit of directions are desired, the surface of thepanel ll] may be sanded by a circular sanding disc which will produceapproximately circular scratches of the type indicated on the surface [3in Fig. 3. The scratches overlap so that the entire surface I3 is almostcontinuously covered by projections which will abrade and hold chalk.

As mentioned above in connection with Fig. 1, the plate In may be of athickness sufficient to be self-supporting and to be used withoutfurther supporting structure as a writing board, but in a preferred formof the invention, the plate of resinous material is made relatively thinand 5. opaque and is applied to a relatively rigid backer of a material,such as wood, pressed board, plates of different resinous material, orsuperimposed layers of wood bonded to each other etc. In Fig. 3, we haveshown a sheet or plate I4 cemented or otherwise fastened to the surfaceof a backer 15 made of wood. The surface [3 of the sheet I4 may beroughened in the manner heretofore described either before or after itis fastened to the surface of the backer I5.

Some of the resins which are suitable for use in constructing thewriting board of our invention, such as methacrylate, polystyrene andsome of the phenolics, can be processed so that they are transparent inthe hardened state. Accordingly, it is possible to apply a sheet ofhard, transparent resinous material to a sheet of material on whichappear figures of various sorts, and to trace the figure on the resinsheet with chalk. In Fig. 4, we have shown a form of the invention, inwhich the transparent characteristics of the above-mentioned types ofresinous materials are used to permit the construction of a novelwriting board. The writing board shown in Fig. 4 comprises a backer l6of relatively rigid material, such as wood, to which is cemented orotherwise fastened a sheet of material H, such as paper. A figure I8 maybe outlined in opaque marks on the front surface of the sheet I! as bydrawing, printing, lithographing, etc., and a sheet [9 of transparentresinous material is cemented on top of the sheet IT, with a clear ortransparent cement. Preferably, the exposed surface of the sheet i9 isroughened by producing scratches on the surface in two mutuallyperpendicular directions, and the surface may be scratched either beforeor after applying the sheet 19 to the sheet I1. In roughening thesurface of the sheet [9, care should be taken to scratch the surfaceonly lightly so that the figure l8 will not be distorted or obscuredwhen viewed throughthe sheet l9.

If it is desirable to use a relatively thin sheet of resinous materialfor the writing portion of the board and if it is considered undesirableto attach the sheet to a backer of relatively rigid material, thewriting board may be constructed in the form shown in Fig. 5. In thisfigure, a relatively thin sheet 20 of resinous material is surrounded bya frame 2| of resinous material formed integrally with the sheet 20. Theboard may be made by treating or forming the resinous material in a moldhaving the configuration of the board shown in Fig. 5, or if desired, itmay be formed by building up the sheet 20 with a plurality of resinimpregnated sheets of fibrous material, superimposing on these sheets aplurality of resin impregnated strips of fibrous material having theconfiguration of the fram 2| and subsequently subjecting the assembly toheat and pressure in a mold having a suitable shape. If desired, thesheets forming the portion 20 of the board may be impregnated with aresin having a color different from the resin used to impregnate thestrips so that the completed board will have a writing surface of onecolor and a frame of another color. After the board has been formed, thesurface 22 of the sheet 20 is roughened in any of the manners heretoforedescribed.

Because the plates of the present invention may be relatively thin andlight, they may beassembled in book form, as indicated in Fig. 6. Thepages 23, 24 and 25 of the book shown in Fig.

6 may be made in the same manner as the plate 10 shown in Fig. 1, andthey may be roughened on one or both sides. The plates may be heldtogether by means of a spiral strip 26 which extends through apertures2! near the edges of the plates, and they may be differently colored soas to be complementary in color to the colors of the chalk used forwriting thereon.

If the book shown in Fig. 6 is intended solely for chalk use, both sidesof each sheet 23, 24

and 25 would preferably be roughened. It is possible, however, to usethe sheets for both chalk and wax crayon writing by roughening one sideof a sheet only and by leaving the opposite side of the sheet in theglossy condition obtained after molding. The glossy surface, althoughnot suitable forchalk writing, will readily receive wax crayon markswhich may be removed by merely wiping the surface with a cloth.

While the principles of the invention have been described in connectionwith a specific form, it is to be understood that the description hasbeen given by way of example only and other modifications thereof, whichwill be readily apparent to those skilled in the art, may be madewithout departing from the scope of the invention which is defined bythe claims appended hereto.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A relatively stiff and rigid, laminated plastic writing board,comprising a plurality of superimposed sheets of fibrous material,impregnated with and consolidated by a thermostat synthetic resin, onesurface of said board being minutely serrated for abrading and holdingchalk, and the opposite surface of said board having bonded thereto alaminated backing consisting of superimposed layers of wood bonded toeach other.

2. A writing board according to claim 1 wherein the abraded surfacelamina of said laminate comprises a clear and transparent resin, andwherein the lamina disposed below said surface lamina has opaquemarkings thereon viewable through said abraded surface lamina.

3. A writing board according to claim 1 wherein said serrated surface issand abraded.

MAC BUXBAUM.

MOE LEBENSF'ELD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 27,818 Mayall Apr. 10, 18601,501,026 Guay July 8, 1924 1,866,312 Loetscher July 5, 1932 1,886,801Freiberg Nov. 8, 1932. 2,011,648 Page Aug. 20, 1935 2,042,210 Clay May26, 1936 2,087,111 Mayall July 13, 1937 2,112,762 Chatfield Mar. 29,1938 2,120,673 Meadows June 14, 1938 2,156,289 Hoy May 2, 1939 2,276,035Guhl Mar. 10, 1942 2,312,623 Brooks Mar. 2, 1943 2,409,645 Sawyer Oct.22, 1946 2,423,076 Daly July 1, 1947 2,452,235 Gold Oct. 26, 19482,504,390 Caldwell Aug. 18, 1950 2,522,351 Egolf Sept. 12, 1950

